Monte Carlo simulations of the classical two-dimensional discrete frustrated φ4 model

The classical two-dimensional discrete frustrated 04 model is studied by Monte Carlo simulations. The correlation function is obtained for two values of a parameter d that determines the frustration in the model. The ground state is a ferro-phase for d = -0.35 and a commensurate phase with period N = 6 for d = -0.45. Mean field predicts that at higher temperature the system enters a para-phase via an incommensurate state, in both cases. Monte Carlo data for d = -0.45 show two phase transitions with a floating-incommensurate phase between them. The phase transition at higher temperature is of the Kosterlitz-Thouless type. Analysis of the data for d = -0.35 shows only a single phase transition between the floating-fluid phase and the ferro-phase within the numerical error.